Stabilising primer????

You could try zinsser gardz, it is a water based sealer that is formulated for problem porous surfaces.
https://www.trade1st.co.uk/media/ca...136e95/z/i/zinsser-gardz-sealer-2.5-litre.jpg

 

Better to give the wall 1 or 2 coats of a stabilising solution first, like Everbuild 406.

http://www.everbuild.co.uk/index.php?route=product/product&product_id=148

Don't know where you are, I can pick it up cheap in Bristol & Salisbury, but look around you can find it cheap.

 

I'd always understood that stabiliser is to stabilise powdery, dusty surfaces, and chust not required on solid fresh render.

Just been using that Everbuild stab on my dusty garage floor prior to painting, and have to say I find it's nifty stuff. But on the properly rendered exterior garage walls, I just slightly watered (10%-ish) the first coat of masonry paint before a couple of neat coats to finish off. That was 10 years ago and absolutely no issues whatsoever.

So if your render is recent and in good order, I wonder if there's any advantage in using stabiliser? It does seem to be designed for loose, dusty surfaces specifically.

 

I had the paint lift off a rendered wall, render was several months old, must have been a bit porous or something, it solved the problem & gave the paint a good adhesion, but I don't use it all the time.
And do NOT put stabilising solution on to a newly rendered surface.
A lot depends on the quailty of the masonry paint you use I think, Sandtex masonry seems to be self priming & never gives me any problems.
As to thining masonry paint some conflicting advice around, some say add 10% water to the first coat, others say never add water.

 

For paint, I guess buy good quality - and follow manufacturer's instructions (chust in case they vary).

Sorry, KIAB, I don't understand a couple of your points above. You say you've had paint come off a rendered wall that was only a few months old, and this was solved by using stabiliser? And then you say stabiliser should not be used on a newly rendered wall? Isn't render just a few months old still fairly 'new'? Are you saying that few months weathering is best, and then you can use stabiliser?

 

He did say several months.

 

A bit of clarification I think DA, render had been on the wall 5-6 months,it was now September, so I considered render fully dry after a hot summer, painted it with masonry paint first coated slightly thinned down, then a second coat about week later.
A few weeks later I found you could pick the paint off,& some areas it came off in big strips.
Ended up stripping whole wall & applying stabilising liquid, follow by two coats of same masonry paint, no problems, paint was still there about 5 years when I moved house.

 

Thanks Mr Ha and KIAB.

Blimey - that's scary, KIAB.

Stabiliser is the way to go, then.

I wonder what the main cause of paint not adhering to render is, tho'? I mean, it should do - it's what it's designed for.

Could it be that the render needs to have the surface layer of alkaline washed off - that's what's meant by a bit of 'weathering'?

It surely should can't be that it hasn't fully dried until a few months has passed - in decent weather it's clearly bone dry within a week?

 

Possibly too dry and porous, sucking the life out of the paint and drying it prematurely!

Mr. HandyAndy - Really